1. Technical Field
The present invention relates to a liquid ejecting head and a liquid ejecting apparatus, each including piezoelectric element that changes the pressure in a pressure generating chamber communicating with a nozzle aperture and includes a piezoelectric layer and electrodes applying a voltage to the piezoelectric layer, and to the piezoelectric element.
2. Related Art
Some of the piezoelectric elements have a structure in which a piezoelectric layer made of a piezoelectric material capable of electromechanical conversion, such as a crystallized dielectric material, is disposed between two electrodes. A piezoelectric element of this type can be used as a deflection vibration mode actuator device in a liquid ejecting head. Ink jet recording heads are a typical type of liquid ejecting head. An ink jet recording head includes a vibration plate defining a part of a pressure generating chamber communicating with nozzle apertures through which ink droplets are discharged. In the ink jet recording head, a piezoelectric element deforms the vibration plate to apply a pressure to the ink in the pressure generating chamber, thereby discharging ink droplets through the nozzle apertures.
The piezoelectric material (piezoelectric ceramic) used for forming the piezoelectric layer of such a piezoelectric element is required to have high piezoelectric properties, and a typical example of the piezoelectric material is lead zirconate titanate (PZT). On the other hand, it is desirable to reduce lead from piezoelectric materials, from the viewpoint of environmental protection. For example, BiFeO3-based piezoelectric materials, which contain Bi and Fe, are lead-free. Among these are piezoelectric materials containing mixed crystals of Bi(Fe, Mn)O3 and BaTiO3 disclosed in, for example, JP-A-2009-252789.
Piezoelectric materials containing Bi, Ba, Fe and Ti result in lower strain than PZT piezoelectric materials disadvantageously. This issue arises not only in ink jet recording heads that discharge ink droplets, but also in other liquid ejecting heads that discharge droplets other than ink.